“ MUSLIM IBN AL-ḤAJJĀJ, the Imam, the author of one of the two books of Mahommedan tradition called Ṣaḥīḥ, “sound,” was born at Nishapur at some uncertain date after A.D. 815 and died there in 875. Like al-Bukhārī (q.v.) , of whom he was a close and faithful friend, he gave himself to the collecting, sifting and arranging of traditions, travelling for the purpose as far as Egypt. ”